1. Field of the Invention
The present invention relates generally to a piping device that diverts oil flow, and particularly relates to a piping device for use in a cutting oil coater for coating a cutting oil over cutting objects and tools in a cutting process.
2. Related Background Art
Conventionally, cutting is carried out while coating oil over a cutting object and a tool so as to improve the cutting accuracy and to extend the life of the tool. If the oil is coated in a droplet state, the cutting can be carried out with the use of a minute amount of the oil, thereby not only improving the processing accuracy and the productivity but also improving the working environment and allowing for the simplification of the factory facilities, etc.
In such cutting, oil may be discharged out of a plurality of outlets so that the operations of oil coating with respect to the cutting object and the tool corresponding to the outlets are performed simultaneously. This is effective in the case where the cutting is performed with respect to a plurality of portions of the object using a plurality of tools. Further, even in the case where one tool is used, the application of oil from a plurality of directions makes the cutting treatment uniform, improves the processing accuracy, and further, suppresses the abrasion of the tool.
FIG. 6 is a plan view illustrating an example of a conventional cutting oil coater. Three spray transport tubes 62a to 62c are connected to a piping device 60 via joints 61a to 61c. The spray transport tubes 62a to 62c are connected with spray generators 63a to 63c, respectively. The spray generators 63a to 63c produce an oil spray (fine particles of liquid oil) by mixing oil supplied from oil tanks 66a to 66c by oil pumps 65a to 65c with air supplied from air sources 64a to 64c, respectively.
The oil spray thus generated is transported to the piping device 60 by the spray transport tubes 62a to 62c. In the piping device 60, the oil spray passes through paths 67a to 67c, and is discharged via outlets 68a to 68c, respectively.
In this case, paths 69a to 69c inside the outlets have a small inside diameter relative to that of the paths 67a to 67c. Therefore, after the oil spray flows into the paths 69a to 69c inside the outlets, the flow velocity of the oil spray increases, thereby changing into a droplet state when being discharged. Thus, in the example shown in the drawing, the oil in the droplet state can be applied in three directions simultaneously to a rotating saw blade 70.
While the example in FIG. 6 is configured so as to be connected with spray generators for all the paths, it may be configured so as to be connected with oil pumps in place of the spray generators. In such a device, oil in a liquid state is transported through paths, and the liquid-state oil discharged from outlets 68a to 68c at ends of the paths is diffused, thereby changing into a droplet state.
FIG. 7 is a cross-sectional view illustrating another example of a conventional piping device. In a piping device 71 shown in the drawing, tubes 74a to 74c are connected to a diverting section 72 via joints 73a to 73c, respectively. Joint main bodies 75a to 75c are fastened to the diverting section 72 using screw threads 76a to 76c thereof, respectively. The tubes 74a to 74c are inserted through sleeves 77a to 77c as fixing members, respectively. Nuts 78a to 78c as fastening members are screwed against screw threads 79a to 79c of the joint main bodies 75a to 75c, respectively, so that the sleeves 77a to 77c are pressed tightly to the tubes 74a to 74c, respectively. Thus, the tubes 74a to 74c are fixed to the joint main bodies 75a to 75c by means of the sleeves 77a to 77c and the nuts 78a to 78c, respectively.
The oil spray supplied from the tube 74a flows into a path 80 inside the diverting section 72, and is diverted to a flow through a path 81 (indicated by an arrow h) and a flow through a path 82 (indicated by an arrow i). The oil spray thus diverted flows into the tubes 74b and 74c, and is discharged finally through outlets (not shown) having narrow diameters, while changing into a droplet state.
However, the foregoing conventional cutting oil coater as described above has the following problems. The device as shown in FIG. 6 has an advantage in that it is capable of making an oil amount coated over the object uniform since it is capable of controlling a flow rate of the oil spray as to each of the tubes 62a to 62c. However, in this case, it is necessary to connect the spray generators 63a to 63c or the oil pumps to all the tubes 62a to 62c, respectively, and this increases the production cost and the complexity of structure.
In the case where the piping device as shown in FIG. 7 is used, a plurality of spray generators are not needed and the device can be simplified. However, there is a drawback in that the flow rates in the paths 81 and 82 that are diverted in the diverting section 72 differ from each other.
More specifically, oil spray is supplied via a tube 74a, in which without a particular selecting means, oil in a droplet state or a liquid state also is transported along with the oil spray. This causes the distribution state of oil in the path 80 to vary, and a state may occur in which oil in a droplet state or a liquid state is distributed unevenly, for instance, residing on a wall on one side in the path 80. In the case where the oil is diverted in this state, the oil in the path 81 and the oil in the path 82 have different flow rates. Therefore, even if the inside diameters of the paths 81 and 82 are set to be equal to each other so that the flow rates at the outlets at the ends of the paths are substantially equal to each other, they differ from each other in some cases, and the relationship between the respective flow rates at the outlets varies with time, thereby becoming destabilized. In this case, it is impossible to make the cutting treatment uniform. This causes a drawback in that the cutting work involves increased variations.
It should be noted that states of oil are described distinctively, such as “spray”, “a droplet state” and “a liquid state”, depending on the diameter of oil particles. The “spray” indicates a fine particle state including a smoke state in which particles of oil are so fine as to drift in air, and comparing oil in the spray state, the droplet state, and the liquid state, the oil particle diameter increases in the stated order. To state reversely, the “droplet state” indicates a state in which oil in the liquid state is diffused, and the “spray” indicates a state in which the oil in the droplet state is diffused further so as to be in the fine particle state. Comparing oil in the spray state, the droplet state, and the liquid state, the tendency of gravitational falling and the adhesiveness to wall faces of oil increase in the stated order. These definitions apply to the descriptions below.